CustomTkinter/customtkinter/scaling_tracker.py

import tkinter
import sys
from typing import Callable


class ScalingTracker:
    deactivate_automatic_dpi_awareness = False

    window_widgets_dict = {}  # contains window objects as keys with list of widget callbacks as elements
    window_dpi_scaling_dict = {}  # contains window objects as keys and corresponding scaling factors

    widget_scaling = 1  # user values which multiply to detected window scaling factor
    window_scaling = 1
    spacing_scaling = 1

    update_loop_running = False
    update_loop_interval = 150  # milliseconds

    @classmethod
    def get_widget_scaling(cls, widget) -> float:
        window_root = cls.get_window_root_of_widget(widget)
        return cls.window_dpi_scaling_dict[window_root] * cls.widget_scaling

    @classmethod
    def get_spacing_scaling(cls, widget) -> float:
        window_root = cls.get_window_root_of_widget(widget)
        return cls.window_dpi_scaling_dict[window_root] * cls.spacing_scaling

    @classmethod
    def get_window_scaling(cls, window) -> float:
        window_root = cls.get_window_root_of_widget(window)
        return cls.window_dpi_scaling_dict[window_root] * cls.window_scaling

    @classmethod
    def set_widget_scaling(cls, widget_scaling_factor: float):
        cls.widget_scaling = max(widget_scaling_factor, 0.4)
        cls.update_scaling_callbacks_all()

    @classmethod
    def set_spacing_scaling(cls, spacing_scaling_factor: float):
        cls.spacing_scaling = max(spacing_scaling_factor, 0.4)
        cls.update_scaling_callbacks_all()

    @classmethod
    def set_window_scaling(cls, window_scaling_factor: float):
        cls.window_scaling = max(window_scaling_factor, 0.4)
        cls.update_scaling_callbacks_all()

    @classmethod
    def get_window_root_of_widget(cls, widget):
        current_widget = widget

        while isinstance(current_widget, tkinter.Tk) is False and\
                isinstance(current_widget, tkinter.Toplevel) is False:
            current_widget = current_widget.master

        return current_widget

    @classmethod
    def update_scaling_callbacks_all(cls):
        for window, callback_list in cls.window_widgets_dict.items():
            for set_scaling_callback in callback_list:
                if not cls.deactivate_automatic_dpi_awareness:
                    set_scaling_callback(cls.window_dpi_scaling_dict[window] * cls.widget_scaling,
                                         cls.window_dpi_scaling_dict[window] * cls.spacing_scaling,
                                         cls.window_dpi_scaling_dict[window] * cls.window_scaling)
                else:
                    set_scaling_callback(cls.widget_scaling,
                                         cls.spacing_scaling,
                                         cls.window_scaling)

    @classmethod
    def update_scaling_callbacks_for_window(cls, window):
        for set_scaling_callback in cls.window_widgets_dict[window]:
            if not cls.deactivate_automatic_dpi_awareness:
                set_scaling_callback(cls.window_dpi_scaling_dict[window] * cls.widget_scaling,
                                     cls.window_dpi_scaling_dict[window] * cls.spacing_scaling,
                                     cls.window_dpi_scaling_dict[window] * cls.window_scaling)
            else:
                set_scaling_callback(cls.widget_scaling,
                                     cls.spacing_scaling,
                                     cls.window_scaling)

    @classmethod
    def add_widget(cls, widget_callback: Callable, widget):
        window_root = cls.get_window_root_of_widget(widget)

        if window_root not in cls.window_widgets_dict:
            cls.window_widgets_dict[window_root] = [widget_callback]
        else:
            cls.window_widgets_dict[window_root].append(widget_callback)

        if window_root not in cls.window_dpi_scaling_dict:
            cls.window_dpi_scaling_dict[window_root] = cls.get_window_dpi_scaling(window_root)

        if not cls.update_loop_running:
            window_root.after(100, cls.check_dpi_scaling)
            cls.update_loop_running = True

    @classmethod
    def remove_widget(cls, widget_callback, widget):
        window_root = cls.get_window_root_of_widget(widget)
        try:
            cls.window_widgets_dict[window_root].remove(widget_callback)
        except:
            pass

    @classmethod
    def remove_window(cls, window_callback, window):
        try:
            del cls.window_widgets_dict[window]
        except:
            pass

    @classmethod
    def add_window(cls, window_callback, window):
        if window not in cls.window_widgets_dict:
            cls.window_widgets_dict[window] = [window_callback]
        else:
            cls.window_widgets_dict[window].append(window_callback)

        if window not in cls.window_dpi_scaling_dict:
            cls.window_dpi_scaling_dict[window] = cls.get_window_dpi_scaling(window)

    @classmethod
    def activate_high_dpi_awareness(cls):
        """ make process DPI aware, customtkinter elements will get scaled automatically,
            only gets activated when CTk object is created """

        if not cls.deactivate_automatic_dpi_awareness:
            if sys.platform == "darwin":
                pass  # high DPI scaling works automatically on macOS

            elif sys.platform.startswith("win"):
                from ctypes import windll
                windll.shcore.SetProcessDpiAwareness(2)
                # Microsoft Docs: https://docs.microsoft.com/en-us/windows/win32/api/shellscalingapi/ne-shellscalingapi-process_dpi_awareness
            else:
                pass  # DPI awareness on Linux not implemented

    @classmethod
    def get_window_dpi_scaling(cls, window) -> float:
        if not cls.deactivate_automatic_dpi_awareness:
            if sys.platform == "darwin":
                return 1  # scaling works automatically on macOS

            elif sys.platform.startswith("win"):
                from ctypes import windll, pointer, wintypes

                DPI100pc = 96  # DPI 96 is 100% scaling
                DPI_type = 0  # MDT_EFFECTIVE_DPI = 0, MDT_ANGULAR_DPI = 1, MDT_RAW_DPI = 2
                window_hwnd = wintypes.HWND(window.winfo_id())
                monitor_handle = windll.user32.MonitorFromWindow(window_hwnd, wintypes.DWORD(2))  # MONITOR_DEFAULTTONEAREST = 2
                x_dpi, y_dpi = wintypes.UINT(), wintypes.UINT()
                windll.shcore.GetDpiForMonitor(monitor_handle, DPI_type, pointer(x_dpi), pointer(y_dpi))
                return (x_dpi.value + y_dpi.value) / (2 * DPI100pc)

            else:
                return 1  # DPI awareness on Linux not implemented
        else:
            return 1

    @classmethod
    def check_dpi_scaling(cls):
        # check for every window if scaling value changed
        for window in cls.window_widgets_dict:
            if window.winfo_exists():
                current_dpi_scaling_value = cls.get_window_dpi_scaling(window)
                if current_dpi_scaling_value != cls.window_dpi_scaling_dict[window]:
                    cls.window_dpi_scaling_dict[window] = current_dpi_scaling_value
                    cls.update_scaling_callbacks_for_window(window)

        # find an existing tkinter object for the next call of .after()
        for app in cls.window_widgets_dict.keys():
            try:
                app.after(cls.update_loop_interval, cls.check_dpi_scaling)
                return
            except Exception:
                continue

        cls.update_loop_running = False